This research is built upon three features: (a) immature sperm do not bind to a hyaluronic acid binding surface, and this serves as an initial marker for cells with impaired development; (b) building from the subset of sperm that do bind [apparently normal in that aspect], it is possible to analyze for other potential abnormalities; and (c) taken together, any sperm that is shown to be absent of abnormalities is a "best" candidate for intracytoplasmic sperm injection (ICSI). The "other potential abnormalities" include: presence of an abnormal protein termed CP64; shorter tail length; DNA breakdown; and chromosomal aneuploidy. Together these could form an important diagnostic test. From this background, specific aims are developed, namely: Aim #1 - use of the hyaluronic bead binding to trap sperm for further detailed analysis; Aim #2 - analysis of tail length as a simple morphologic detection of sperm immaturity; Aim #3 - analysis of chromosomal abnormalities via comparison of bound vs. non-bound cells; and Aim #4 - extension of the above to testicular biopsies and analysis of spherical spermatids.